In addition to monitoring the quality of education in national systems, the PISA empirical results provide the necessary evidence base for making changes to both policies and practices in education. In this regards, this chapter presents evidence from two systematic reviews of the impact of large scale assessments including PISA on educational policy. Particular attention is given to the types of assessment programmes undertaken, their goals and uses, the stages of the policy process informed by assessments; and the facilitators of and barriers to the uses of assessment data in the educational policy-making process. This chapter concludes with considerations regarding how the capacities of large-scale assessments to inform both policy development and implementation may be increased.